Explain how complex fractions can be used to solve problems involving ratios?

Complex fractions are fractions whose numerators and denominators also consist of fractions. Since they are technically fractions, they can be used as ratios. Suppose the complex fraction which is used as ratio for 2 + 3/4 cups of flour to 1 + 2/3 cup of milk. The ratio would be

(2 + 3/4) / (1 + 2/3)

Just simplify it using the concept of greatest common factor:

((4(2) + 3)/4) ÷ ((3 + 2)/3)
11/4 ÷ 5/3

When you encounter division of fraction, take the reciprocal of the divisor, then change the operation to multiplication:

11/4 × 3/5 = 33/20

The simplified ratio is 33/20. So, if you want to use 5 cups of flour instead, the corresponding cups of milk would be:

33/20 = 5/x
x = 3.03 cups of milk

So, that is how you use complex fractions as ratios. I just provided an example to show explicitly how it could be used.